Secretary of State John Kerry and Russian foreign minister Sergei Lavrov announce a plan to eliminate Syria's chemical weapons arsenal from Geneva on Saturday.

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Saturday, the U.S. and Russia announced an agreement on the destruction of Syria's chemical weapons. The country has a week to detail its chemical arsenal and has until the middle of 2014 to destroy its stockpile. The State Department has published a framework for the plan.

Amy Smithson, a senior fellow at the Monterey Institute's James Martin Center for Nonproliferation Studies, gets back to the basics of chemical weapons — what they are, where they came from — with NPR's Jacki Lyden.

The Origin Of Syria's Chemical Weapons Capabilities

"Initially, the Syrian chemical weapons program was very dependent on outside expertise and materials coming in from the outside," Smithson says.

In the 1990s Syria appears to have received assistance from Iran and Russia in the form of the "precursor chemicals" (ingredients for the weapons) as well as technical support, she says, "and North Korea also came into the equation then with assistance on delivery systems."

"But quite some time ago, the program appears to have transitioned to one where Syria has the domestic capacity to do all this," Smithson says. "In other words, they have production facilities, apparently, for them that are capable of making chemical warfare agents."

What Counts As A Chemical Weapon?

The Organisation for the Prohibition of Chemical Weapons, or OPCW, defines chemical weapons as "any toxic chemical or its precursor that can cause death, injury, temporary incapacitation or sensory irritation through its chemical action."

The delivery devices for the chemicals, filled or unfilled, "are also considered chemical weapons themselves."

Smithson says there are two basic forms of chemical weapons: unitary and binary. Those classified as unitary are already mixed before being loaded into munitions.

With binary weapons, the last two precursor chemicals can be mixed at the last minute and then loaded into the munition. Or those chemicals can be stored separately inside of the munition, and on the way to the target, the membrane between the chemicals bursts, creating a deadly mixture.

In terms of making the weapons, Smithson refers to the saying, "A bozo can make it in a beaker."

"To make the chemical warfare agents, a chemist with fairly rudimentary experience is probably going to be able to synthesize a small quantity of these agents," she says. "But to scale up to large quantities, the types of things that militaries often have to have in order to use them on the battlefield, that's a whole other ballgame."

The Daily Beastpublished an article in August, a few days after the chemical attack in Syria, breaking down the types of chemical weapons that have been used historically.

How To Inspect, Destroy Chemical Weapons

When inspectors are sent into a country, they inspect production facilities and storage sites to first take inventory, Smithson says.

"So they're literally going to be in the field counting munitions and closing down production facilities. Out of that, there will be a determination made about what destruction processes would be best for this particular arsenal," she says.

One of their most important jobs, Smithson says, is watching the weapons being destroyed.

"They also go to commercial facilities that produce significant quantities of the chemicals that can feed into a chemical weapons program, but under legitimate circumstances are in the products that we make use of in our homes and lives every day," she says. (The OPCW goes into more detail about the issue of balancing these possible uses with their potential to harm.)

Modern chemical warfare is traced back to World War I. The Geneva Protocol, prohibiting the use of chemical and biological weapons in war, was signed in 1925. But the U.S. didn't ratify it until 1975.

"And when it did, it reserved the right to retaliate in kind if chemical weapons were used against U.S. forces. That's largely because this was Cold War-era, and the Soviet Union had a large chemical weapons program," Smithson says.

The U.S. position changed again in 1991, when President George H.W. Bush publicly renounced the right to retaliate in kind.

When they arrive on the ground, U.N. chemical weapons inspectors will have a daunting task. U.S. intelligence agencies say the Assad regime has amassed enormous stockpiles of sarin and mustard gas despite an international ban on manufacturing deadly chemical agents.

Amy Smithson is a senior fellow at the Monterey Institute's Center for Nonproliferation Studies. She joins us to explain how Syria got these weapons in the first place. Amy Smithson, welcome to the program.

AMY SMITHSON: Thank you. It's a pleasure to be with you.

LYDEN: So one of the big enduring questions is exactly where Syria got these weapons from or how it created them. It's no surprise that bad people get their hands on chemical weapons, but what steps have to be taken in order to do that?

SMITHSON: Initially, the Syrian chemical weapons program was very much dependent on outside expertise and materials coming in from the outside. In the 1990s, it appears to have transitioned to assistance from Iran and also in the early 1990s from Russia where precursor chemicals, the ingredients that go into making these warfare agents were provided as well as technical assistance. And North Korea also came into the equation then with assistance on delivery systems.

But quite some time ago, the program appears to have transitioned to one where Syria has the domestic capacity to do all this. In other words, they have production facilities apparently for them that are capable of making chemical warfare agents.

LYDEN: So what level of expertise does someone have to have in order to use these deadly agents?

SMITHSON: The saying is that a bozo can make it in a beaker. To make the chemical warfare agents, a chemist with fairly rudimentary experience is probably going to be able to synthesize a small quantity of these agents. But to scale up to large quantities, the types of things that militaries often have to have in order to use them on the battlefield, that's a whole other ballgame.

LYDEN: You mentioned that Syria now has the capability to use these precursor chemicals themselves. Is there a difference between, say, sarin and VX when these things are created?

SMITHSON: Sarin and VX are both nerve agents, a family of chemicals that directly attacks the nervous system. The initial chemicals that appeared on the battlefield were actually chemicals that are still used in the commercial industry today for legitimate purposes. But the organophosphorus chemicals that feed into nerve agents are often used in fertilizers and pesticides. And Syria is believed not only to have mustard gas but also nerve agents sarin and perhaps even VX.

LYDEN: And they're so toxic that they really can only be combined near to the time that they're going to be used, right?

SMITHSON: Well, there are two basic forms of chemical weapons. The unitary weapons are ones that are already mixed. And when they're loaded into a munition, harm occurs, death can even occur. But with what is known as a binary weapon - and Syria may have this capability - the last two precursor chemicals may either be stored separately outside of the munition and mixed at the last minute, then loaded into it or actually stored separately inside of the munition. And on the way to the target, this membrane between those two chemicals burst. There's mixture that takes place in flight and, boom, sarin.

LYDEN: So what happens in the destruction process?

SMITHSON: Plans will take shape to go in and inspect the sites that are declared as production facilities and also as storage sites. An inventory will be taken, so they're literally going to be in the field counting munitions and closing down production facilities. Out of that, there will be a determination made about what destruction processes would be best for this particular arsenal.

LYDEN: And there'd be an outside international presence, a number of inspectors, teams that would be on the ground at these various sites.

SMITHSON: Yes. That's one of the most important jobs that the international inspectors have done. They literally sit there and watch the weapons being destroyed. They also go to commercial facilities that produce significant quantities of the chemicals that can feed into a chemical weapons program, but under legitimate circumstances are in the products that we make use of in our homes and lives every day.

LYDEN: How has the U.S. response to the use of chemical weapons changed over the years?

SMITHSON: The Gulf War - the first Gulf War actually started to change our equation in terms of our policy. When the Geneva Protocol was passed in 1925 - this is the treaty that bans the use of chemical weapons - the United States actually didn't ratify it until 1975. And when it did, it reserved the right to retaliate in kind if chemical weapons were used against U.S. forces. That's largely because this was Cold War era and the Soviet Union had a large chemical weapons program.

But in 1991, President George Bush made a very public statement renouncing the U.S. right to retaliate in kind. So our policy began to change even before the United States joined the Chemical Weapons Convention, which put everybody - 189 countries at this point - on the same level playing field. Nobody possesses it, nobody uses it.

LYDEN: So, Amy Smithson, at the end of 2003, Libya announced that it would get rid of its chemical weapons, began that process the next year, didn't receive a ton of attention at the time. What do we know about how Libya was divested of these terrible chemical weapons?

SMITHSON: The assessment was made initially by U.S. and British teams but then confirmed by the international inspectors that Libya had a stockpile of mustard gas that needed to be destroyed both in munitions and, I believe, also what's called bulk agent. In other words, agent that is sitting in containers but not yet loaded into weapons. And the United States and the United Kingdom began providing assistance to help Libya destroy this arsenal.

And when Libya forfeited its weapons of mass destruction programs at the end of 2003, early 2004, inspectors went in and found that the Libyans were unsuccessful in producing nerve agents because they couldn't scale up, but they certainly did have a stockpile of mustard gas.

LYDEN: Where else might there be stocks of chemical weapons? I mean, we've talked about Libya. Is there suspicion that they are elsewhere?

SMITHSON: Indeed, indeed. And the finger points at Pyongyang. Not only does North Korea have a chemical weapons capability, they also have a biological and nuclear weapons capability, the unfortunate trifecta in terms of international peace and security.

LYDEN: Amy Smithson is a senior fellow at the Monterey Institute's James Martin Center for Nonproliferation Studies. Amy Smithson, thank you so much for your time.

SMITHSON: It's been a pleasure to be with you. Transcript provided by NPR, Copyright NPR.